1. Field of the Invention
The present invention relates to a developing apparatus. More specifically, the present invention relates to a developing apparatus using a dual-component developer wherein carrier and toner are mixed.
2. Description of the Prior Art
One example of a developing apparatus which is interesting to the present invention is disclosed, for example, in the Japanese Patent Publication No. 19505/1985 published on May 16, 1985.
In this developing apparatus of prior art, swelling of a developer is formed at the central part of a screw conveyor, and a level of this swelling of the developer is detected by level sensing means, and thereby the density of toner to carrier is detected. This prior art has a disadvantage that the swelling of the developer at the central part of the screw conveyor not always reflects accurately the toner density, and accordingly the detection of the toner density is inaccurate.
More specifically, in general, when the toner density is low, fluidity of the developer is increased, and an effect of rotation of a blade becomes large, resulting in a large pulsation of the level. On the other hand, when the toner density is high and the fluidity of the developer is small, the swelling sometimes falls down. Accordingly, the above-described prior art cannot detect an accurate toner density because the level of the developer does not correspond accurately to the toner density.